Electric discharge device including improved anode structure



June 24, 1958 H. N. PRICE 2,840,746

ELECTRIC DISCHARGE DEVICE INCLUDING IMPROVED ANODE STRUCTURE Filed Oct. 22, 1956 INVENTORI HARVEY N. PRICE BYWMW ms ATTORNE ELECTRIC DISCHARGE DEVICE INCLUDING IMPROVED ANODE STRUCTURE Harvey Price, .Sco'tia, NL. YL, assignor to General Electric Company, a corporation of New York v Application October 22, 1956, Serial No. 617,362 3 Claims. 01. 313-217 The present invention relates to electric discharge de-' vices, and more particularly to improved gas-filled electrio discharge devices including new and improved means adapting same for increased power level operation.

Currently, gas-filled electric discharge devices such,

high-refractory ceramic envelopes and-externally extending electrode elements thereby, respectively, to withstand and eflic'iently dissipate the increased heat. Additional ly, in the type of. device to which the present invention is particularly applicable the anode assembly generally includes a metal cup-like sealing member comprising part of the envelope of the device and having afbottompor tion which is re-entrant 'in'the envelope and serve'sas.

the active anode surface. For desired satisfactory operation this bottom portion or active surface of the' seal. ing member must be maintained planar and parallel to other electrodes in the device; and thesealing member must not be distorted so as to crack the metal-to-ceramic seals between the anode assembly and ceramic portions of the envelope. Maintaining the active surface in the mentioned planar and parallel relations and avoiding sealdamaging distortions have been problems owing to' a tendency of the sealing member to be distorted as a result of atmosphericpressure at operating temperatures and during cooling following brazing of the structure to the associated ceramic portions of theenvelope. These problems have been aggravated by the fact that, from the standpoint of providing suitable brazes between the cup-like sealing member and the ceramic portions of the envelope, it is desirable that the sealing member be formed of relatively thin material and preferably copper, which construction affords little resistance to distortion stresses. Heretofore, it was attempted to cope with this problem by bonding a relatively massive stiffening plate to the outer surface of the bottom or active portion of the sealing member. This solution has not proved completely satisfactory, especially in high power level devices characterized by high heat generation, first, because of tendencies toward distortion resulting from thedifferentials in expansion and contraction rates between thecopper and steel and, secondly, because the relatively massive steel plate tended both to retain heat and to shield a substantial portion of the relatively more heatconductive copper sealing member from the normally cooling air currents, thereby resulting in decreased'cooling efiiciency. Furthermore, in high power level operation the electron and ion bombardment of the internal elements and surfaces of the device is so substantial that it has been found necessary to secure to the inner surface of the mentioned cup-like sealing member a highrefractory metal element adapted for serving as the active anode surface. -This element has alsobeenafound to cause distortion of the anode assembly during .cooling after brazing because ofa diiferential inltherrrial expar'ie.

2,840,746 Patented June; 24, .1 58,

sion and "contraction rates between "thermaterials of thfe'f element, the copper sealing memberfand the externally disposed steel stiffeningplate. In order (to alleviatejthi s" condition it has been proposed to s'ecurefthe sealing" member and the high-refractory elements at only limited? corresponding centralportions. This type of'structure," however, is not considered satisfactory in thatlt wouldhave the adverse effects of reducing substantially the: heat transfer from the active anode surfacetdthefer ternal portion of "the sealing member andthus tendfto" render the device'less adapted for high power"level"op-" erationf 1 Accordingly, the primaryobject of the present inven tion is to provide a new and .improve delectric discharge" device adapted for increased-high'power level operatic in'.

Another object of the present invention is to providef a new and improved gas filled electric discharge device? including new and improved means forgincreasing' heat dissipation therefrom; Q y 5 Another objectof the present invention 'is to' provide" anew and improved gas' filled electric discharge device including new and improved means for maintaining dc sired, electrode spacing therein and insuring against sealing failuresfi' i z Further'objects and advantages of the presentinven tion will become apparent as the following description proceeds and the features of-novelty which characterize ing members which'are thin relative to 'the insulators and include substantial portions extending externally of the envelope; One of-the electrode assemblies' is anode assembly comprising a clip-like sealing member re-' entrant in' the associated ceramic insulator. Bonded to that surface; of this member which is disposed internally of th'e envelope is a' high-refractory metal element c'orilprising a planar active anode surface. 1 Bonded to the opposite surface of the'sealing member" is a member which 'occupies an inappreciable volume in the bottorn of the sealing member, is formed of low heat retentivity material and is of substantially similar thermal expansion andfcontraction characteristics as thehigh refractory metal element. Carried 'by the member disposed in the bottom of the sealing member is a he'atradiating element.

For a better understanding of the invention reference may be had tothe accompanying'drawing whereinfis illustrated an electric discharge device constructed in" accordance with a preferred embodiment of thepresent"; invention. i V 1 j The electric discharge device there illustrated'is a hy drogenfthy'ratron comprising .an envelope 1,'a cathode reservoir assembly '2, a grid assembly} and ban; anode assembly. 4. 'j I n 1 J The envelope '1 comprises three generally cylindrically ceramic sections 5, 6 and 7. The sections 5-7 may be r 3 January 26, 1954 to Henry J. Nolte and assigned to the same assignee'as the present invention.

The cathode-reservoir assembly 2 includes a header closing the lower .end, of,.th e envelope 1 and generally designated 8. The. header 8 supports in a suitably mutually, insulative manner a plurality of leads 9 which extend throughthe header in a sealed manner and internally of theenvelope support and make suitable elec-' trical connections to the cathode structure and a hydrogen reservoir (not shown). Secured to the leads 9 are flexible conductors 1.0, each carrying a lug 11. The header 8 further includes a sealing ring 12 which is bonded to a suitably. previously metalized lower edge of the insulative section 5, as by means of a silver-copper brazing material. By way of example, and with a ceramic which had been metalized by the above-mentioned titanium hydride process, the brazing material may comprise approximately 72% silver and approximately 28% copper and thebraze may be effected in a hydrogen furnace in a temperature range approximately between 778 and 850. Also, suitably bonded to the exterior of the ring 12 is an annular metallic flange 13 adapted for facilitating mounting of the device.

'thus contributes to the cooling of the device.

outwardly of the insulative sections of the envelope, aitrld T e member 25 includes a plurality of protrusions 28 which can be substantially identical in construction and purpose to the protrusions 20 in the member 19.

The sealing member 25 is substantially re-entrant in the upper portion of the insulative section 6 for thus disposing the planar bottom portion 27 thereof in substantially close parallel spaced relation to the planar grid element 21. Bonded to that surface of the bottom portion 27 which is disposed internally of the envelope 1 is a disk-like element or plate 30 formed of a high-refractory metal which is'preferably molybdenum. The plate 30 is preferably about .060.070 of an inch Internally of the envelope, the sealing ring 12 may be suitably electrically connected to the above-mentioned cathode structure which is shown in outline and generally designated 14. Thus, the ring 12 and associated flange 13 are adapted for conjointly serving as the electrical contact for the cathode.

I As illustrated in the drawing the cathode structure 14 can include a shielding structure including a cylinder 15 suitably mounted about the upper end of the cathode structure 14, a plurality of wire-like supports 16 extending radially inwardly from the upper edge of the cylinder 15 and an imperforate metallic disk-like member or shield 17 secured centrally on the supports 16. In this arrangement the diameter of the member 17 is less than that of thecylinder and thereby is effective for enabling passage therepast of electrons originating at the cathode while at the same time effecting the desired shielding.

Sealed between the opposed edges of the ceramic insulators 5 and 6, as by substantially the same brazing process described above in respect to the sealing ring 12, is a sealing ring 18. The sealing ring 18 comprises a rim-like portion of an inverted cup-like grid support structure 19. Formed in the side wall of the member 19 adjacent the ring 18 is a plurality of circumferentially spaced outwardly extending protrusions 20. The protrusions 20 are engageable with the inner wall of the ceramic section 6 for insuring maintenance of a desired spaced relation between the upper portion of the member 19 and the section 6 during operation of the device. The grid proper comprises a perforated bottom portion 21 of the structure 19 and a perforated plate 22 secured in spaced parallel relation to the bottom portion 21 as by a plurality of circumferentially arranged brackets 23. The perforations in the plate 22 and the perforations in the portion 21 of the member 19 are in ofiset relation so as to avoid straight direct passage of electrons and ions therethrough. Disposed centrally between the portion 21 and the plate 22, for the purpose of ma' taining a desired spaced relation therebetween, is a spacer element 24.

The sealing ring 18 serve both as an electrical contact forthe grid and extends substantially outwardly for increased heat dissipation.

The anode assembly 4 comprises a cup-like sealing member 25 including a rim portion 26 and a.planar bottom portion 27. The member 25 is preferably formed of' copper and'is relatively thin compared to the insulative sections. The rim portion 26 is bonded between previously metalized opposed edge portions of the ceramic insulative sections 6 and 7 in the same manner asthe grid sealing ring18, between the sections 5 and 6.

' tions.

and is bonded to the anode sealing member completely throughout the opposed areas thereof, as indicated at 31, and the bond is preferably effected by means of a gold-copper alloy brazing material with the braze being effected in a hydrogen atmosphere at approximately 1050 centigrade. The inwardly facing surface of the member 30 serves as the active anode surface of the assembly 4 and is substantially planar and equally spaced from the planar surface of the grid member 21 throughout the corresponding portions thereof. The high-refractory nature of the material of the plate 30 adapts the active anode surface to withstand without deterioration greater electron and ion bombardment and, thus, the device is adapted for efiicient higher power level opera- Additionally, the gold-copper alloy braze completely across the opposed surfaces of the sealing member bottom27 and the element 30 provides for maximum heat transfer from the active anode surface to the anode sealing member 25 for heat dissipation thereby, which As. seen in the drawing the rim 26 extends substantially V ment 30, and as at 32, is an element 33.

feature further adapts the device for eflicient high power level operation.

Bonded to the external surface of the portion 27 of the sealing member 25 or the surface opposite the ele- T he element 33 is formed of a material and to a thickness and configuration whereby it is adapted for having substantially the same thermal expansion and contraction characteristics as the element 30. Thus, the member 33 is adapted for backing up or reinforcing the bottom portion 27 of the sealing members 25 and the high-refractory material plate 30without adversely affecting the electrode spacing or ceramic-to-metal seals at the rim 26. Additionally, the element 33 is formed of a material having low heat retentivity' and which will provide the desired thermal expansion and contraction matching characteristics relative to the element 30 Without filling any appreciable volume of. the cup-like sealing member 25. As seen in the drawing, the element 33 covers only the bottom of the member 25 and, thus, leaves the sidewall portions of the member 25 exposed to air currents therein for maximum heat dissipation from the device. Preferably the member 33 is formed of the same dimensions and material as the element 30. However, it will be understood that, inasmuch as the member 33 need not be formed of a high-refractory metal, it is not essential that it be formed of molybdenum or the like.

Suitably bonded centrally in the member 33 and in satisfactory electrically conductive relation with the elements comprising the anode assembly is an upstanding stud or connector 34, adapted for serving as the anode contact. Additionally, disposed about the stud 34 and bonded to the member 33 is a hollow cylindrical metal element 35 adapted for serving as a heat radiator thereby to increase heat dissipation from the anode assembly 4.

Thus, it will be seen that I have provided a new and improved gas-filled electric discharge device including new and improved means for increasing heat dissipation therefrom, maintaining desired electrode spacing and insuring against sealing failures during assembly and subsequent operation, whereby the device is adapted for efficient higher level power operation.

While the specific embodiment of the present invention has been shown and described, it is not desired that the invention be limited to the particular form shown and described, and it is intended by the appended claims to cover all modifications within the spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric discharge device comprising, an envelope including a cylindrical insulative section, an electrode assembly including a conductive memberof thin metal extending across one end of said insulative section, said member being bonded to said one end of said insulative section and extending substantially outwardly therefrom, a metal plate bonded to one surface of said member for serving as an active surface of said assembly, and a member of low heat-retentivity material and having substantially the same thermal expansion and contraction characteristics as said plate bonded to the opposite surface of said conductive member.

2. An electric discharge device as in claim 1, including a heat radiating element bonded to said member of low heat-retentivity material.

3. An electric discharge device comprising, an envelope including a cylindrical insulative section, an electrode assembly including a conductive member of thin metal extending across one end of said insulative section and bonded at the outer edge to said insulative section, a high-refractory material plate bonded to the surface of said conductive member facing into said cylindrical section for serving as an active electrode surface, and a plate of substantially the same thermal expansion and contraction characteristics as said first-mentioned plate bonded to the opposite surface of said conductive memher.

4. An electric discharge device comprising, electrode structure including an anode assembly, an enclosing envelope including a cylindrical insulative section, said anode assembly including a conductive cup-like member of thin metal having a bottom portion re-entrant in one end of said insulative section and a rim portion bonded to said insulative section, and identical metal plates bonded to the opposite surfaces of said bottom portion of said member.

5. An electric discharge device as in claim 4, including a hollow cylindrical heat-radiating element disposed in said cup-like member and bonded to the metal plate on the corresponding side of said bottom portion.

'6. A gas-filled electric discharge device comprising, electrode structure including an anode assembly, an enclosing envelope including a cylindrical ceramic section, said anode assembly including a cup-like member of conductive material having a planar bottom re-entrant in one end of said ceramic section and a rim portion bonded to said ceramic section, a high-refractory metal plate extending and completely bonded across the surface of said planar bottom innermost in said ceramic section for serving as the active anode surface of said device, and a thin metal plate of substantially the same thermal expansion and contraction characteristics as said firstmentioned plate extending and completely "bonded across the opposite surface of said planar bottom of said conductive member.

7. A gas-filled electric discharge device comprising, electrode structure including an anode assembly, an enclosing envelope including a cylindrical ceramic section, said anode assembly including a cup-like member of thin metal and having a planar bottom re-entrant in one end of said ceramic section and a rim portion bonded to said ceramic section and extending substantially outwardly therefrom, a thin molybdenum plate bonded to the surface of said planar bottom facing into said ceramic section for serving as the active anode surface of said device, and a plate of substantially identical dimensions and material bonded to the surface of said planar bottom opposite said first-mentioned plate.

8. In an electric discharge device a cylindrical insulator, a thin sheet metal member extending across one end of said insulator and bonded thereto, said member being solely supported by said insulator and including a peripheral portion extending radially substantially outwardly from the side walls of said insulator, and a pair of similar metal plates bonded completely thereacross to opposite surfaces of said sheet metal member, one of said plates serving as an active electrode and the other cooperating with said one plate for minimizing distortion of said sheet metal member therebetween.

9. An electric discharge device comprising a cylindrical insulator, a metal member extending across one end of said insulator and bonded thereto, said member being solely supported by said insulator, and a pair of similar metal plates bonded completely thereacross to opposite surfaces of said metal member, one of said plates serving as an active electrode and the other cooperating with said one plate for minimizing distortion of said metal member therebetween.

' 10. An electric discharge device as in claim 9, includ ing a heat dissipating member bonded to said other metal plate. 

